Hard coatings based on thermal spray and laser cladding

Thermal spray and laser cladding have been used to develop hard coatings. HVOF and laser glazing techniques were used to form hard and corrosion resistant coatings, using WC/Co, impregnated in Ni-Cr powder, to protect the heat exchanger tubes from fireside erosion and corrosion, while PM 20 alloy (chromium carbide in Ni-Cr powder), WC/Co in Ni-Cr powder were used to develop a very hard and friction resistant coatings for engine groves, using plasma spray and laser cladding techniques. Results indicate that an optimized composition (15-30% of WC/Co in NiCr matrix) was best to control the erosion and corrosion of heat exchanger tubes and PM 20 alloy, applied using laser cladding, gave excellent hardness and adequate wear and friction resistance. (C) 2008